TM 1-1510-225-10 3C-35 bearing pointers (OSA) the RMI bearing pointer (ANG) will drive to the park or 3 o'clock position and the HSI NAV warning flag will be in view.  In the ILS mode, the bearing pointer(s) will remain in the park position. Table 3C-2.  Diagnostic and Fault Codes CODE DESCRIPTION AND COMMENT CODE DESCRIPTION AND COMMENT 00 No fault found. 18 VOR  AFC  not  locked.    VOR  unusable  (no  rf signal). 02 RAM test failed.  Unit unusable (µP problem). 19 Low 30-Hz reference signal.  VOR unusable. 03 No  serial  data  to  unit.    Unit  unusable  (CTL problem). 20 Low 30-Hz variable signal.  VOR unusable. 04 No   serial   frequency   word.      Unit   unusable (CTL problem). 21 400-Hz  power  supply  unusable.    VOR  OBI and OBS unusable. 05 Invalid  NAV  frequency.    (CTL  may  be  tuned to DME channel). 22 OBI sin out of tolerance.  VOR OBI and OBS unusable. 06 Microprocessor fault.  Unit unusable. 23 OBI    cos    out    of    tolerance.        VOR    OBS unusable. 10 Microprocessor fault.  Unit unusable. 24 OBS   return   out   of   tolerance.      VOR   OBS unusable. 11 Analog to digital fault.  Unit unusable. 25 LOC   synthesizer   unlocked.      LOC   receiver inoperative. 12 Analog  to  digital  failed  accuracy  test.    Unit unusable. 26 LOC signal level low.  LOW unusable. 13 +13 Vdc power supply fault.  Unit unusable. 27 LOC     deviation     out     of     tolerance.          LOC deviation unreliable. 14 -13 Vdc power supply fault.  Unit unusable. 28 GS    synthesizer    unlocked.        GS    receiver inoperative. 15 VOR    sin     è/LOC    digital    to    analog    fault. VOR/LOC unusable. 29 GS signal too low.  GS receiver inoperative. 16 VOR    cos     è/GS    digital    to    analog    fault. VOR/GS unusable. 30 GS deviation out of tolerance.  GS deviation unreliable. 17 VOR   receiver   synthesizer   unlocked.      VOR receiver inoperative. 32 Marker beacon fault.  Observe marker lamps for fault. NOTE During ILS operation, the NAV 1 and NAV 2 deviation relays are monitored by a failure warning  system.    Failure  of  one  of  these relays will be indicated by the appearance of the HSI NAV and/or VERT flags.  3C-22.  TACAN SYSTEM. a.    Description.    The  TACAN  system  operates in    conjunction    with    TACAN    and    VORTAC    ground stations   to   provide   distance,   groundspeed,   time-to- station,  and  bearing  to  station.    Figure  3C-16  shows the TACAN control panel and Figure 3C-17 depicts the TACAN indicator.  It operates in the L band 1000 MHz frequency range on one of 252 pre-selected frequencies,  126  X  mode  and  126  Y  mode  channels. Course deviation and distance to TACAN or VORTAC stations are displayed on the HSI.    Distance,  time-to- station,  and  groundspeed  are  displayed  on  the  HSI.   Distance, time-t o-station, and groundspeed are displayed    on    the    TACAN    digital    display.        The groundspeed  and  time-t o-station  are  accurate  only  if the  aircraft  is  flying  directly  toward  the ground station at a sufficient distance that the slant range and ground ranges  are  nearly  equal.    The  system  is  protected  by the  TACAN  circuit  breaker  on  the  avionics  portion  of the copilot's right sidewall panel.